I've been on a guns question binge lately, and this is no exception. Given my previous questions about vanishing projectiles and explosive alkali metals inside bullets, I started thinking of other chemical reactions, except this time not in the form of the projectile, but rather the propellant.
Similar to how baking soda volcanoes or airbags work, using a catalyst and substance that react violently to each other utilizing valves that let only a certain amount mix could provide a very effective and quick propellant. The more explosive the mixture, the faster the projectile could be flung.
This obviously leads me to my main question:
Would such a system work for a chemically powered gun, and what mixture would I need to use to achieve it?
Note: Per the comments, I realized I made a mistake. I'm not looking for fire-based chemical reactions, but there does need to be a reaction occurring, preferably with liquids.