Nonequilibrium phase transition in rapidly expanding matter

Nonequilibrium features of a first order phase transition from the quark-gl uon plasma to a hadronic gas in relativistic heavy-ion collisions are discu ssed. It is demonstrated that strong collective expansion may lead to the f ragmentation of the plasma phase into droplets surrounded by undersaturated hadronic gas. Subsequent hadronization of droplets will generate strong no nstatistical fluctuations in the hadron rapidity distribution in individual events. The strongest fluctuations are expected in the:vicinity of the pha se transition threshold.