Studying Phase Transitions in Nuclear Collisions

In this talk I discuss three main topics concerning the theoretical description and observable signatures of possible phase transitions in nuclear collisions. The first one is related to the multifragmentation of thermalized sources and its connection to a liquid-gas phase transition in finite systems. The second one is dealing with the Coulomb excitation of ultrarelativistic heavy ions resulting in their deep disintegration. The third topic is devoted to the description of a first order phase transition in rapidly expanding matter. 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.