How quickly does ethanol evaporate? Suppose I open the drinks cabinet, and pour some of the strong stuff into a saucepan.

Now the boiling point of ethanol is lower than water, so if I boil the mixture for a while, all the alcohol will surely evaporate long before the water does.

But how quickly does the alcohol evaporate? Is it all gone by the time the water starts to boil? Or does some remain unless you boil the mixture for a long time? (How long?) Or maybe the alcohol is gone by the time the mixture starts to get slightly warm?
Certainly water and ethanol and all mixtures thereof will completely evaporate without boiling given enough time.  

Water and ethanol form a postive azeotrope that is 95.6% ethanol and 4.4% water and boils at 78.2 degrees C.

If you boil a mixture of water-ethanol that has less than 95.6% ethanol, the concentration of water in the liquid phase will increase, but it will only asymptotically approach pure water as all the liquid boils away.  There will not be a time when all the ethanol is gone and you are left with a finite amount of pure water.  

If you boil a mixture of water-ethanol that has more than 95.6% ethanol, the concentration of ethanol is the liquid phase will increase.