Solubility of compound in acid I have a substance that is insoluble in water but soluble in hydrochloric. If dissolve this substance in the acid, would neutralizing the solution with sodium bicarbonate then cause the substance to separate from solution?
Yes, you've described a property of amines. When protonated by an acid (e.g. $\ce{HCl}$), an amine is converted into into a water soluble salt. This is actually a thing to do in pharmaceuticals to increase the amount of a drug that can be dissolved in water and be taken up by the body. The next time you have the chance take a close look at the chemical names on a drug label and theres a good chance you might see "hydrochloride."

Just as something can be protonated, it can be deprotonated. For the hydrochloride salt of an amine, $\ce{NaHCO3}$ should be basic enough to deprotonate it, and cause it to precipitate out of solution, as it would no longer be a water-soluble salt.