  Solidification of droplets is of great importance to various technological
applications, drawing considerable attention from scientists aiming to unravel
the fundamental physical mechanisms. In the case of multicomponent droplets
undergoing solidification, the emergence of concentration gradients may trigger
significant interfacial flows that dominate the freezing dynamics. Here, we
experimentally investigate the fascinating snow-globe freezing dynamics of
supercooled ethanol-water droplets. We reveal that these unique freezing
dynamics are driven by solidification-induced solutal Marangoni flow within the
droplets. We quantitatively characterize the concentration-dependent migration
and growth dynamics of ice particles, tightly connecting them to the solutal
Marangoni effect and the associated convective heat transfer. Moreover, we show
that the final wrapping state of droplets can be modulated by the concentration
of ethanol. Our findings may pave the way for novel insights into the
physicochemical hydrodynamics of multicomponent liquids undergoing phase
transitions.
