As deadly as it is beautiful, chlorine's characteristic yellow hue turns to a viscous, deep yellow-orange liquid when pressurized to over 1000(!) Psi - as in this little ampoule. If you were to heat this cube in boiling water (don't though!) it would cross the supercritical liquid-vapor point and the liquid would appear to vanish. After cooling down it would suddenly condense back out into a half and half state.