For burnt on messes in your frying pan or sauce pans: fill with inch or so water then add tsp of salt & bring to a boil. let boil a minute or two then wash.
I think it's actually better to wash your make-up brushes every day, if you do make-up, because it collects the bacteria, especially if we are talking about some liquid make up like foundation
It's also good to spray them and your dry make-up (like eye shadows) with alcohol, to kill the bacteria