In the framework of quantum electrodynamics (QED), the universally accepted theory of ordinary condensed matter, we analyse a system of ions dissolved in water. Contrary to the common opinion that for aqueous solutions in normal conditions, QED can be well approximated by classical physics or by the semiclassical approximations of molecular dynamics, we find for such systems QED solutions of a very different nature. Such solutions appear to solve several paradoxes that plague the conventional approaches. Our main result is that ions dissolved in water are not in a gaseous state, but settle in a coherent configuration, where they perform plasma oscillations in resonance with a coherent electromagnetic field, thus providing a satisfactory understanding of the thermodynamics of electrolytes. In this new framework, we also find a simple explanation of the phenomenon of osmosis.