system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is there so much smoke produced after a fire goes out?

Even if the material seems to burn clean before it goes out.
gpt
When something burns hotly, it burns cleanly. When you take away the flame, it has enough embers and residual heat to continue smoldering, but without the heat of the flame the result is incomplete combustion resulting in smoke and soot. 

Details: 


What is smoke? It's soot, and carbon compounds, tar, aerosols, un burned fuel, and other components of incomplete combustion. When a fire burns brightly and hotly, it efficiently combines oxygen with carbon to make carbon dioxide and carbon monoxide, and with hydrogen to make water vapor. 

If all of the hydrocarbons and organic material being burned are done so cleanly, then there is very little smoke and instead an almost pure reaction resulting in carbon dioxide and  water which are odorless and transparent gases. IE not smoke. 

When a flame is extinguished but there is still a lot of latent heat, the process of burning is snuffed out resulting in incomplete transformation into the water and carbon dioxide, leading to incomplete compounds which create the soot.