Hello I hope some of you can help and shed some light as to why my candle has gone bubbly at the top after it's first 3/4 hour burn? The wax is a mix of rapeseed, beeswax and steric acid. I added 10% (ratio to wax) essential oil to it. I let it cure for 1 week. The scent throw was great when cold and when I lit it too, but once it cooled again this is how it looked. Any help would be greatly appreciated! Thank you, S.