HI Kannan,

 

The balloon pops up when your currently opened chat window(s) has a new messeage arrived. Everytime an agent comes and go, they triggers a new message in the "Agents" room. If you have that "Agents" window open, certainly you will get notified for their online/offline status change. If you don't care about their status, simply close the "Agents" window and the messages will go away.

 

Glad to help