Burning Fuels and Producing Water

The air in the kitchen is warm enough and dry enough that the water vapor isn't condensing. If you want to see it, take a pan and fill it will ice water, then put it over the flame. You'll see the water vapor condensing on the outside of the pot.

Because the water vapour/$CO_2$ mixture is very hot. Then it mixes with the surrounding air and dilutes too much to condense. This why you can't "see" it.

But hold a really cold pan in the flame and initially you'll see water condense onto the surface of the pan. Then the pan heats up and the condensation evaporates again.