Our back patio is constructed of 2x2' aggregate cement blocks. The
surface isn't made up of those really big stones, but neither is it
smooth. This patio has been in place for almost 14 years and thus is
probably stable and will not shift.

My question is, what options do I have to lay tile over this instead?
I hate the look of this cement and want to get rid of it. Do I have
to completely pull it out and put in a smooth concrete patio first?
Can I just use leveling mud and put hardiboard backerboard over the
concrete? Can I lay a thin layer of smooth concrete over the existing
pieces? Obviously I don't want the tile that I put down to crack
shortly after this project.

Thank you!
-Rex