video How to Freeze Water While Boiling
This can actually happen. It seems unnatural, but the laws of physics don't lie. Liquids require heat to boil, and if the conditions are right one liquid can be boiled in order to freeze a second. Under a vacuum, the water in an acetone/water mixture can freeze while the acetone boils. Watch the video and see for yourself.
How to do this
Fill flask with 25mL of acetone and 10mL of water
place in a bell jar with a vacuum and turn on
Imagine cooling some water to just above it's freezing point at ambient pressure. Now imagine pulling a strong enough vacuum to boil the water. Water has a very high heat of evaporation, so boiling will lower the temperature of the remaining water and ice ought to start forming as the liquid boils. (Evaporation is a cooling process. That's why we need to sweat.)* Eventually you'll run out of liquid and the ice will start subliming, just like snow can in really dry cold weather.
Notice I said "ought" and "imagine" and did not specify how strong a vacuum you need. Basic thermodynamics says it ought to work if you can lower the pressure enough. But I don't plan to try it and I recommend that only people who have experience with high vacuum work even consider trying it. Implosions throw a lot of broken glass around and can kill or maim anyone nearby.
PS, I don't think you can pull a strong enough vacuum with an aspirator, no matter how strong the flow, because the water in the aspirator would boil before the water in your sample. One would need a strong vacuum pump, vacuum grade equipment and the experience to use it safely. Or one could get an astronaut to try it during a space walk.
* The fact that water expands upon freezing will help because that means that lowering the pressure will raise the freezing point.
Our video of the experiment is here on youtube.
http://www.youtube.com/watch?v=y4nPwztC-eU