The emergence of superconductivity in certain metals when cooled below a critical temperature is an example of a phase transition.
At the end of each phase there is a phase transition revision at which the program management decides if the program is ready to move to the next phase (the end of transition is product release).
They discovered a first order phase transition, a discontinuity, in liquid hydrogen between a molecular state with low conductivity and a highly conductive atomic state.
You have a phase transition from one crystal to another.
