I might add that the heat softens the lignin which is the glue that =
holds
the fibers together. When it is soft the fibers can move relative to =
each
other (very slightly) and relieve most of the stress in the piece. =20

More on point is that this is exactly what happens when steam bending =
wood. Perhaps boiling's success isn't that it lets wood dry faster, but =
with less checking?