A small amount of water sits on a watch glass. The watch glass is placed on top of a specially cut pyrex beaker that contains a small amount of sulfuric acid to absorb water vapor. The set-up is placed inside a plexiglass vacuum chamber. The entire apparatus is placed on an overhead. When the vacuum pump is activated, the water boils. The boiling continues for a few minutes until the water freezes. Often, a bubble trapped in the ice can be observed, i.e. at one time water exists in all three phases.
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