The physical ionic change repels Silica, Alumina and Iron which normally act as binders and make scale form. Free electrons are generated which allow Ca (Calcium) and Mg (Magnesium) to dissociate from Co3 (Carbonate), So4 (Sulphate) and SCO3 (Hydro carbonate) and assume their neutral atomic sates. Thus stopping scale forming and removing scale deposits.
On evaporation only neutral minerals form and any Calcium Carbonate left will form as neural Aragonite instead of Calcite as shown above. Aragonite is stable at high pressures, it is also 19 times more soluble than calcite.