Explanation:

- Combustion: This involves burning a substance in the presence of oxygen, releasing heat and light. Firecrackers explode due to rapid combustion of chemicals.

- Precipitation: This process relates to the formation of a solid from a solution. It is mostly used to describe rain, sleet, or snow falling from clouds. Not relevant here.

- Decomposition: This is a process where a compound is broken down into smaller substances, often through chemical reactions. Firecracker explosions aren't simply decomposition.

- Evaporation: It is the process where liquid turns to gas, usually when heated. Again, irrelevant to firecracker explosions.