Indeed - plenty of cooking processes can produce gas bubbles that are trapped or escape leaving foam structures behind that take up considerably more space than the original material. Like bread, for example.
The volume of flour and water you put into a dough is considerably less than the volume of the loaves you'll produce - and a significant amount of the water you put in will have gone by the time they're cooked (also you'll have lost some of the carbohydrates from the flour which has been turned into CO2 and ethanol by the yeast, a bunch of which will also cook out of the loaf).
The volume of flour and water you put into a dough is considerably less than the volume of the loaves you'll produce - and a significant amount of the water you put in will have gone by the time they're cooked (also you'll have lost some of the carbohydrates from the flour which has been turned into CO2 and ethanol by the yeast, a bunch of which will also cook out of the loaf).