GJ 1214b is a water-world 40 light-years away from Earth. While this exoplanet’s total mass is thought to be ~25% rock & ~75% water, not all of this water is in our familiar liquid form.
Being so close to its star, with surface temperatures around 200-500˚F, the outer layers are thought to be composed of mainly… steam. Inner layers would contain more condensed forms of water, including liquid, plasma, and high-pressured ice.
It is unclear how these layers break down, if they do at all. It is possible that there are no defining lines between liquid and vapor layers that exist. Liquid water may gradually become thinner and thinner until it is a gas. It is also possible that the liquid layer might boil and bubble with incredible force spewing water and gas in massive ejections similar to our own solar flares.
Luckily, this exoplanet is one of few that can have its atmosphere studied. It will occupy scientists for years, and there is much more to learn.
GJ 1214b on Wikipedia