Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, [Image: see text]. Here we report a universal water-content, [Image: see text], dependence of [Image: see text] for aqueous solutions. Solutions with [Image: see text] vitrify/devitrify at a constant temperature, [Image: see text], referring to freeze-concentrated phase with [Image: see text] left behind ice crystallization. Those solutions with [Image: see text] totally vitrify at [Image: see text] under conventional cooling/heating process though, [Image: see text] of the samples annealed at temperatures [Image: see text] to effectively evoke ice recrystallization is stabilized at [Image: see text]. Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of [Image: see text] by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution.