This invention provides processes for forming solution compositions, which processes comprises bringing together, in an aqueous medium, i) at least one phosphorus compound; ii) at least one Group VI metal compound; and iii) at least one Group VIII metal compound, such that a solution having a Group VI metal concentration of more than about 5.6 mol/L is formed. Also provided are compositions formed by such processes, processes for forming catalyst compositions from these compositions, and catalyst compositions formed by these processes.