  This study deals with a simple pure fluid whose temperature is slightly below
its critical temperature and whose density is nearly critical, so that the gas
and liquid phases coexist. Under equilibrium conditions, such a liquid
completely wets the container wall and the gas phase is always separated from
the solid by a wetting film. We report a striking change in the shape of the
gas-liquid interface influenced by heating under weightlessness where the gas
phase spreads over a hot solid surface showing an apparent contact angle larger
than 90{\textdegree}. We show that the two-phase fluid is very sensitive to the
differential vapor recoil force and give an explanation that uses this
nonequilibrium effect. We also show how these experiments help to understand
the boiling crisis, an important technological problem in high-power boiling
heat exchange.
