Combustion of Product

Yes.

"Yes"

But not very much, not enough to cause concern unless its a very big "confined chamber"

You don't have to worry about you wife blowing up the kitchen stove oven!

Usually the problem is on the component. They got too hot and start burning.

I set a piece of brownie on fire in the microwave once.

Pineapple

An over-microwaved Christmas Pudding is far more spectacular....

I once tried to sterilize some potting compost (which was composed of sand, bark chips, humus etc, but also had slug and snail eggs in it, having been left outside in an unsealed bag).

Method: Bung in the microwave on defrost for 5 minutes.

Result: A small fire, and lots of acrid smoke. (Killed the eggs, tho' )

Am I missing something here? Why would one get "combustion gases" from a flour - water mix at 350 F?? What's the ignition source? Is the water vapor being removed from the oven?