This is an interesting thing to me, imagine a spherical container filled with a perfect hydrogen to oxygen fuel air mixture, there is an ignition source(such as a spark plug) in the container. So you light off the gasses, what happens to the pressure in the container? My resoning says obviously it spikes immediately, but then what happens, water is much more compressed than the gasses, so you've burned the hydrogen, and water is your result, because of the compression factor of the gasses into water, would it pull a vacuum on the container? and if it did, would it boil the water and keep it in a vapor state? are there any other byproducts in the container?