Not an expert on grain but in general vibration will aerosolize particles (preferentially the smallest ones) and it's amazing what will burn when you aerosolize it as a fine powder.
That's mostly due to the physics of how it's being aerosolized.
We used to take individual serving packets and do giant flame spikes. We got a large can of it and did the same thing from the top of a stairwell with someone on the bottom floor with a lighter and someone up top with the creamer.
We hadn't fully considered the ramifications of our actions until we saw the fireball coming up at us.
But basically, even without the fire, it would have made the mushroom cloud.
Anything even mildly combustible can make a pretty big fireball.