There’s something like it in UI Router Extras, but as far as I can tell, it just keeps the view around.
Bending UI Router until it breaks: parallel states, view recycling & more
Dario Gieselaar
56

Here’s how you might use UI-Router Extras “Sticky States” to build a modal that does not modify the URL: http://plnkr.co/edit/Nuw7X4?p=preview

After setting up the base sticky state, simply define your modal state as a peer to the base state, but do not give it a “url” property.