First, if there's a lot of wax, take a basic butter knife (an old one which will be used for this purpose only). Score the wax. Some wax may even come close this way. (A flathead screwdriver can be used instead of the knife).
Instead of boiling the container, pour boiling water into the container. Wax has a tendency to float when water is introduced. Let it cool some and then remove wax pieces. Pour out water into a can. (you don't want bits of wax in your sink or going down the drain).
Next, take a piece of paper towel and wipe out wax still there (the container should still be warm). If more wax
remains, repeat process of adding boiling water, etc. A second pour and wipe does the job.
Once the wax is out, clean as you would any glass vessel.