In Secret Garden, why throw water?

In the Korean show Secret Garden, why does the mother keep threatening to throw water at Gil Ra Im? In a few episodes before she does it she threatens to throw water at Gil Ra Im's face (or at least that's how it comes out in the translations). Why?

I would understand if it was a heat of the moment kind of thing, but why threaten to do it before actually doing it? Is this a cultural thing, or just a weird thing of the mom?