The term cononsolvency has been used to describe a situation in which a polymer is less soluble in a mixture of two cosolvents than it is in either one of the pure solvents. If we move into the field of protein stability, then it becomes a desirable feature the fact that the protein become “collapsed” or, better said, folded in a certain solvent mixture. Cononsolvency is thus closely related to the suppression of protein denaturation by stabilizing osmolytes. Cononsolvency behaviour has been found even for small amphiphilic molecules dissolved in methanol/water mixtures. Using a combination of Raman-MCR spectroscopy and MD simulations, it was shown that TBA aggregation is more pronounced in the mixtures than in either of the pure solvents. A thorough structural investigation of TBA solutions is proposed to help the interpretation of thermodynamic and spectroscopic data.