  In this talk I discuss how a first order phase transition may proceed in
rapidly expanding partonic matter produced in a relativistic heavy-ion
collision. The resulting picture is that a strong collective flow of matter
will lead to the fragmentation of a metastable phase into droplets. If the
transition from quark-gluon plasma to hadron gas is of the first order, it will
manifest itself by strong nonstatistical fluctuations in observable hadron
distributions. I discuss shortly existing experimental data on the multiplicity
fluctuations.
