If you're interested in exploring macros, it is really easy to write a macro to hide and show text boxes. This can be activated with a click on a button or on text or with a mouse over. Check out the examples in Chapter 6 at
Just set the ActionSettings to run the macro on Mouse Over
If you're not interested in that, you can fake the effect by having several slides that are identical except that each has a different text box showing. A click (or Mouse Over) on some text can hyperlink you to one of the other slides