Salem

I boiled 4 deer hooves in a clay pot and they only go to 99 percent done. The first time I did not have 100 percent full of water so I took them out, filled the water, and boiled them again. Same result, 99 percent done. What is going on here?

Keep your fire lit for longer.

alternatively, if there is not enough water in the pot to boil the hooves, they'll get stuck at 99% (similar to limed hides not turning to leather). For leather you can solve this by just pouring in another bucket of tanning fluid which will immediately turn a limed hide to leather. However, for pots this is not possible as refilling it (STILL, darnit) requires taking the hooves out. So make sure there is enough water in the pots (1L per hoove, iirc? might be .5L too).
If they are stuck with more than the required amount of water in the pot, then the heat of the fire has gone out.
Just re-light the fire and wait until completion (which may take a while because it takes a while for the pot to register the heat of the fire when you light the fire after the pot is put over the fireplace).

Relighting the fire without removing them worked. It was actually the Aether that was 0.99% and I misread that as the amount complete. They were short of complete but not stuck at the last percentage.