I use a gas range for my boils, and never really have a problem with heat/burn issues. I used to turn the gas off, and move the pot when adding extracts, but have sinced just turned the gas down to the lowest setting. Nothing has burned on me yet.
However, during yesterday's brewing of a stout, I was doing a late addition of my DME with a pretty high boil temp, and I came darn close to a boil-over. I haven't come that close in a looooong time, but then again, never did I actually ever boil-over in my homebrewing past either!
Something to note though:
There are times when I am in the boil, and the wort feels to be sticking to the bottom of the pot, however it is not... I found that this is just the feeling of the boiling bubbles that form when doing an... um... BOIL! hahaha In any case, I stir frequently to play it safe.
5gB