How do the physico-chemical properties and character of phase transformations change when the size of the physical systems decreases below 0.1 μm? It is not easy to give a definite answer to this apparently simple question, though it is important both for fundamental and applied science. This short review focuses mainly on obtaining finely divided aqueous systems on voluminous powder of fumed silica and its study with nuclear magnetic resonance (MNR) and differential scanning calorimetry (DSC). The importance of the study for resolving the mystery of liquid water and the implication of the results to polar stratospheric clouds (PSCs) are discussed.