that'll teach you

My daughter lives in Australia. When I asked her about the recent election, she told me that she had had trouble voting, maybe because she had only registered during the last hour of the last day of the registration period. In response I said to her, "That'll teach you to leave things till the last moment."

Just think about that sentence. If I teach you to play the piano, I hope that my teaching will help you to improve a bit; and if I teach you phonetics, I also expect you to learn something about phonetics.

So why do we say "That'll teach you to ...." when what we mean is exactly the opposite. What I really meant was: That will give you a good lesson NOT to leave things to the last moment.

So why do we say exactly the opposite of what we mean? And how come people understand a sentence like the one I used without batting an eyelid, and usually without noticing that there might be something peculiar about it?

Language is sometimes a deep mystery!