A very long time ago I performed an experiment in my kitchen, part of which was to remove all water from a solution. Unfortunately I don't remember what was in it, but the point is that as the solution got more concentrated, it gradually stopped boiling, and would instead remain completely still for seconds, until a huge bubble would form instantly at the bottom of the test tube, making a pop sound and shooting some of the solution out of the tube. The effect got stronger and stronger until it became too strong for me to feel safe to continue.
I was unable to get an explanation of this effect out of my school teachers at the time. What I expected was that as the solution got more concentrated, the dissolved compound would start to precipitate, until eventually no water is left. Why did the popping occur instead?