Nuclear multifragmentation produced in heavy ion collisions can be described in terms of phase transitions and critical phenomena. For this purpose, the size (charge) distribution of the largest fragment produced in each event has been studied in terms of a decomposition into two contributions: one from an ordered and one from a disordered phase. In the theoretical description of aggregation processes (percolation and Smoluchowski models), where the order parameter is the size of the largest cluster, such a decomposition is also observed and allows to define the pseudo-critical domain of the underlying phase transition. By analogy with these models, we use the evolution of the relative population of the two phases with bombarding energy to localize the pseudo-critical domain for experimental multifragmentation data measured with INDRA. In a second step we present a more detailed comparison with the Smoluchowski aggregation scenario to address the time-scale of the multifragmentation process.