  Late-stage coarsening in off-critical vapour-liquid phase separation is
re-examined. In the limit of bubbles of vapour distributed throughout a
continuous liquid phase, it is argued that coarsening proceeds via inertial
hydrodynamic bubble collapse. This replaces the Lifshitz-Slyozov-Wagner
mechanism seen in binary liquid mixtures. The arguments are strongly supported
by simulations in two dimensions using a novel single-component soft sphere
fluid.
