Does epub have the concept of a pop up window?

For example, it would be great if I had a book, and using the navigation tools, be able to select a part of the book (much like how a link is represented when an HTML file is converted to epub format), and then hit "open" but instead of going to a new location, it would simply pop up a window with some text. When the reader is done, he could dismiss the window and be back where he originally started.