Hello GardenBanter users

I moved house somewhat recently to Africa and I have been experimenting with different kind of plants now that I am in a climate that can grow them. I have planted and grown several bonsai trees during my stay however something suspicious is happening with them...
On a paticularly hot or bright day the plants seem to sweat as a human would, visibly dripping from the leaves. Is this normal? I have not had this with any other plant and it is definitely not dew. My theory is that the plant juice within is seaping out somehow because of the heat.
My neighbours who also keep bonsai trees (The Tickle family, I get my seeds from them) find this confusing and have told me to apply vaseline on the leaves as to restore their naturally waxy protection. The problem with the vaseline route I have found though is that the bonsai tree slides away at night - I have found my trees miles from my home after a windy night.
Thanks for reading, I hope somebody can help.