I was sure it did - we recently had a thread about it.
Anyway, I guess the explanation is that the first few flour particles set alight light their neighbors and so on so rapidly that the heat and flame and smoke cannot escape without smashing everything in their path. Or maybe there is a daemon of kaboom reliably summoned by carelessly deployed flour, soot or coal dust near an open flame. It doesn't really matter - my point at the bottom was that it was a known phenomenon and a magus willing to put up with some burns playing with powdered fuel and a candle (or who talked to someone who had) would find out how easy it is to recreate. You can't just scream Aristotlean physics and expect people to have been stupid and blind.