In order to detect cluster formation in aqueous electrolyte solutions and the existence of extense clusters and phase separation, the structure of a 1.0 M LiF solution was determined by molecular dynamics at 293 K. An ad hoc potential was developed to model the interionic interactions. The resulting data indicate that all the ions had formed a large and unique cluster. The cluster formation and large aggregations depend on the ionic radii because they are responsible for the intensity of the electrostatic interaction at short interionic distances. The unique LiF cluster suggests a phase separation between the solute and the solvent. This conclusion is consistent with the low solubility of LiF. The initial steps of the aggregation of the ions can be compared to the formation of nanocrystals and to the formation of crystal seeds.