When wax gets too hot, it begins to vaporize and is extremely dangerous at this point. I imagine different types of waxes acting differently in this situation. For example, I imagine a paraffin wax would evaporate in stages as it is comprised of several different hydrocarbons mixed together, so this could explain the situation above. The lighter oils evaporated out.
Beeswax will evaporation and become highly flammable -thin Greek fire. We know the ancient Greeks did in fact use molten beeswax as a weapon, it burns very hot, is sticky, and almost impossible to extinguish once it gets going good and hot.
The point of all of this is, don't try and get your wax to high temperatures, you might just burn the house down
240 degrees is UHT levels. This is not necessary, 165 degrees for a minute or two is more than sufficient.