If you mean by "on the hard side" -- all the way to the stop -- every power steering car does this, and you should probably avoid doing it.
I think it'* simply the power steering motor trying desparately to continue to turn your wheels when there'* no way they can be turned further. You're not cranking that hard, but IT is.
(If that'* not what you mean, then somethings wrong. First thing to do of course is check your ps fluid level and add fluid if necessary. Next might be to pop the serpentine belt and grab and check the power steering pulley for grinding, excessive play, hard to turn etc.
Maybe this is more answer than you wanted