Is there a stack that let the user get an info bubble when mouse pass over a button or icon?
PopDrop stack for RapidWeaver is great but not sure about a circular bubble.
Jo Workman has the TipTip Stack for RapidWeaver which is like a browser tooltip but more customisable. Again, not sure you can make it round like a bubble.
@Manofdogs is totally correct - PopDrop will do this easily. A mobile-like bubble can be easily styled with weight, border and fill colour and radial corners - plus (amazingly) a tip arrow auto positioning responsively.
Thin, easy to use (Settings and Examples for the PopDrop stack)
A no-brainer for what you want imo.