To be specific i will give a live example:
http://www.shopcade.com/rodrigopires/lists/5415e86366a92f4f158b4848/funky-shoes
At this page when a product is clicked it opens a frame-like page. On this page you can navigate through products. But when you click the close button, you can always go back to list page.
I believe history api has been used, but i really don't understand how they stored whole page content through all navigation.
There's a very similar demo application explained here:
https://css-tricks.com/using-the-html5-history-api/
It uses Ajax, which I suspect your example also uses.