Thermodynamic stability and Statistical mechanical theory are applied to a model of a zwitterionic tripeptide of sequence Gly-Ala-Gly in high-concentration NaCl solution. It is found that many peptide conformations cannot exist in equilibrium with the salt-water solvent as a single liquid phase. This suggests a single explanation for salting proteins into and out of solution, unique biologically active protein structures, and small energy differences between denatured and folded states, while also implying a mechanism for the resolution to the Levinthal paradox.