[genewitch]

I was thinking more of Mr. Wizard's demonstration of flour blown through a plastic tube into a funnel containing said flour (or whatever) with a flame above it made a "whoosh" type flame ball.

or places that mill anything that don't clean their rafters, who then get a tool crashing into a work piece, which shakes the building, which throws all the dust into the air, which is then sparked off by literally anything. like low humidity.

see also another example; Domino Sugar explosion.