An electrodynamic balance has been used to probe rapid mass transfer processes in single aerosol droplets. Measurements can be made with a resolution of as low as 2.5 ms over a timescale from under 100 ms to many hours. The experimental setup has been used to make vapour pressure measurements on simple single component organic systems as a means of benchmarking the probing techniques. Measurements of rapid evaporation of volatile solvents (water, ethanol) have been conducted and an analytical mass flux model employed to understand the interplay between the physical parameters which determine heat and mass transfer rates. Non-equilibrium systems have been investigated, observing gel formation in MgSO4 and glass formation in sucrose, and the measurements of the timescale for a change in RH have been conducted.