Elucidation of the molecular-level mechanics underlying the dissolution of salts is one of the long-standing, fundamental problems in electrolyte chemistry. Here we follow the incremental structural changes that occur when water molecules are sequentially added to the ternary [MgSO4Mg](2+) ionic assembly using cryogenic vibrational predissociation spectroscopy of the cold, mass-selected [MgSO4Mg(H2O)(n=4-11)](2+) cluster ions. Although the bare [MgSO4Mg](2+) ion could not be prepared experimentally, its calculated minimum energy structure corresponds to a configuration where the two Mg2+ ions attach on opposite sides of the central SO42- ion in a bifurcated fashion to yield a D-2d symmetry arrangement. Analysis of the observed spectral patterns indicate that water molecules preferentially attach to the flanking Mg2+ ions for the n <= 7 hydrates, which results in an incremental weakening of the interaction between the ions. Water molecules begin to interact with the sequestered SO42- anion promptly at n = 8, where changes in the band pattern clearly demonstrate that the intrinsic bifurcated binding motif among the ions evolves into quasilinear Mg2+-O-S arrangements as water molecules H-bond to the now free SO groups. Although condensed-phase MgSO4 occurs with a stable hexahydrate in which water molecules lie between the ion pairs, addition of a sixth water molecule to one of the Mg2+ ions in the n = 11 cluster occurs with the onset of the second hydration shell such that the cation remains coordinated to one of the SO42- oxygen atoms.