As the owner of a lava lamp, I have two things to add to this:
1) There is a warning in the usage/assembly instructions against using other devices to heat the lava tube.
2) He may have been trying to melt the little globs of wax that seperate from the main glob and stick to the sides, reducing the asthetic value of the lamp as a whole. I had considered trying to free up those bits of wax, but having read the warning labels, and, you know, some science books, I knew about Boyle's Law.
I will say this; I have decided that I will leave well enough alone insofar as my lava lamp goes.