Why is it that really sticky labels seem to be used on items where you could do with an easy removal. I've experienced this on a new glass panel door, shower screen and new window panes during a house refurb. Unfortunately while a little warm water can help in many cases, when faced with stubborn super sticky adhesive, you need something a little stronger.
I keep some Eucalyptus oil on hand for this very problem.
Time: 2 minutes
Materials Eucalyptus Oil
Soft Cloth / kitchen towel
Window cleaner or soapy water
Dampen part of a cloth or kitchen towel with a little eucalyptus oil and rub lightly over the sticky last label.
Leave for a few moments to allow the oil the soak in.
Gently rub the label with the cloth to remove the sticky adhesive.
Repeat steps above for really sticky labels until all has been removed.
Now you just need to get rid of the oily residue. Use some warm soapy window or window cleaner.