ooh good points adadw and ken! For anything to burn it needs a fuel (for example oxygen) and energy, so it you deprived it of that fuel, put it in a vacuum maybe, that would mean you could heat it without burning, and so get it to its melting point.
I had a quick google but couldn’t find any videos of this, but it sounds possible to me…
I’m not so sure… I think that before you melt the wood itself (which is mainly cellulose) you’d have reactions of the wood with itself, forming ever more complicated clusters + macromolecules of carbon.
I think you’d probably also chemically drive the water (both loose in the wood & bound up in carbohydrates) out of the cellulose and end up with some horrific coal-like blackened mass that just gets ever more cross linked.
Of course, you will eventually decompose the atoms as you heat, but you may jump directly to a gas (i.e. it will sublime), or even a plasma.