many fluxes require a "saponifier" to get rid of the bothersome "white precipitate" that one sees.
That's why good cleaning liquid ('a flux cleaner') contains not only pure IPA, but some (10-35 %) amount of some benzine/gas, e.g. nefras (pure gasoline) etc (don't know the right English/Americal equivalent).
Yes, it stinks much (better for me
), but it does its job without 'a white residual'.