Our universal approach is by no means restricted to binary electrolyte solutions, but can be generalized to electrolyte mixtures and solutions in general. This requires an additional summation over all possible (neutral) solute combinations in the observation droplet and their interaction with the solute mixture in the environment. The proposed change of perspective offers new insights into the average thermodynamic properties of electrolyte solutions and the connection to local structural heterogeneity and ion complexes characterized by state of the art spectroscopic and simulation techniques. We hope these findings will contribute to the understanding of concentrated electrolyte solutions, which are of relevance in many biological and electrochemical applications in nowadays society. ments and the composition of the solution as