Only if you install the Desktop Application version of the Client. Even then, it just gives you a "Show" button which, when clicked, brings up the interface so you can answer the interaction.
https://help.mypurecloud.com/articles/desktop-app/
Or you can install the PureCloud for Chrome app and extension:
https://help.mypurecloud.com/articles/install-purecloud-for-chrome/
That browser windows is "always-on-top" so it doesn't get hidden behind other applications...though that's not exactly what you're looking for, since you probably want PureCloud hidden until a call comes in, and just answer it from a notification without disturbing the rest of your work.