What can this chemical be? (Qualitative Analysis) I have an unknown white powder, which is an ionic solid, and I need to identify what it is by using qualitative analysis. I've run quite a few tests, but I am having a lot of trouble identifying the anion. The data I've collected is below.
General Properties:

It is a white powder, and I know that it is an ionic solid.
It's density is around $\pu{2g/mL}$ (this is not an exact number)
It appears to be a hydrate (as it loses mass when heated over a bunsen burner)
It is fairly soluble in water. It definitely isn't very insoluble, but I have to add a significant amount of water in order to get it to dissolve.
The powder has a very strong smell (although it's hard to describe).
A solution of the solid is colorless.

Cation Test

A flame test produced a deep orange / orange-red flame

Adding $\ce{Na2CO3}$ to a solution of the solid results in the formation of a white precipitate

Adding a base, such as $\ce{NaOH}$ to a solution of the solid results in the formation of a white precipitate


Based on this data, I am fairly confident that the cation is calcium, but please correct me if there are any other metals that fit the pattern described above or if additional tests are necessary.
Anion Test
This is what has really been messing with me, because I can't seem to get a conclusive test for any anion.

Adding $\ce{AgNO3}$, $\ce{BaCl2}$, or $\ce{Pb(NO3)2}$ to a solution of the solid did not result in the formation of any precipitate, regardless of how much I added.
Adding $\ce{H2SO4}$ results in the formation of a white precipitate (and no bubbles or anything). However, I'm fairly sure that this precipitate is not related to the anion, but rather producing $\ce{CaSO4}$ (from the cation).
Adding $\ce{HCl}$ or $\ce{HNO3}$ to a solution of the solid did not result in any bubbles (neither did adding $\ce{H2O}$ directly to the pure solid)
Adding Ferric Nitrate to the solution just retained the orange color of the ferric nitrate. A dark red color or precipitate was not observed.
Adding $\ce{HCl}$ did not result in the smell of vinegar.
Adding $\ce{AgNO3}$ followed immediately by $\ce{HNO3}$ also did not result in a precipitate.
Adding ammonium molybdate and nitric acid to the solution and heating it caused the solution to turn yellow, but did not yield a precipitate (even after centrifuging). This test was done twice with different ratios of ammonium molybdate to nitric acid, and the exact same result was observed both times.
The brown ring test was conducted, and came back with a negative result. It is possible that this test was done wrong, because the acidified ferrous sulphate was added drop by drop on top of the solution, rather than by rolling it down the side of the test tubes, which may have interfered with test results.

Are there any tests for ions that I have missed? I've done almost every test I know trying to identify the anion, but no dice. The results for the ammonium molybdate test are also confusing to me, because I expected either a yellow precipitate (to confirm phosphate) or no reaction, but the test seems to have gone halfway by just turning yellow. Any guidance on what I should do next would be very much appreciated.
What about a possible $\ce{F-}$ anion? While the nature of the cation might be guessed based on the flame test, since the $\ce{AgNO3}$ test gave no precipitate, it might have produced $\ce{AgF}$ (soluble in water).
This said, by looking at the densities of $\ce{M-F}$ systems with a cation with orange flame and density around $\pu{2 g ml-1}$, I'd say it's probably $\ce{NaF}$.
You might test for fluoride with a selective electrode, if you have one.
Otherwise, here are listed some other analytical methods for the identification of fluoride anions:PubChem: Sodium Fluoride-Analytical Methods