A supercritical fluid exists without a distinct liquid or gas phase and forms when temperatures and pressures exceed the substance’s critical point. Here supercritical transition is demonstrated with an ampule of liquid chlorine. When immersed in a hot bath, the temperature and pressure inside the ampule rises until around 0:20 when the meniscus marking the interface between liquid and gas disappears. The chlorine is now in its supercritical state. Around 0:43 the hot bath is removed and the chlorine begins to cool, reverting to distinct phases of matter around 0:55.