system
Given the following post, respond as if you're commenting on Reddit:
human
Why does wood skip the liquid stage of matter?

Every time wood burns, it always appears to skip the liquid stage of matter. Is this true? If so why does this happen? If it's not true then what is actually happening when wood burns?
gpt
Wood doesn't even enter the gas phase when it gets hot.  When you heat a solid up, all the bonds holding the material together start jiggling, including those bonding interactions that keep different molecules stuck together.  If you keep on heating, one of those interactions can jiggle fast enough to break apart.

For a small molecular solid like water ice, the first thing to break will be all the intermolecular interactions that are holding different molecules together, allowing it to melt and evaporate.  For very large molecules like the lignin that makes up the rigid portion of wood, there are so many intermolecular interactions that it takes an incredible amount of energy to break them all at once.  It's so much energy, in fact, that by the time you've added enough heat that you *could* break all of those intermolecular interactions, you also have added enough energy to break apart the chemical bonds holding the individual molecules together.  

When this happens, we call it pyrolysis instead of evaporation, because the pieces that break off and either become liquid or vapor are not the same molecules as the one that existed in the solid.