I am a first responder and one of our protocols when entering any unknown lab environment is to turn off any burners. Most of the time, we try to not disturb the environment as much as possible so a colleague of mine and myself were curious as to any substance that would actually be more dangerous after turning off said burner. Thank you.
Well, in theory, a few compounds could become explosive when crystallizing out of a solution (which is promoted by low temperatures) though I do not think that "turning off burners" would be enough. The "best" candidate I can imagine would be "azidoazide azide" which can detonate for... just any reason! But nobody uses it, just because of that.