Are you wanting to know how you can recreate this feature?
I believe that they are using iframes so the page is never “really” reloaded.
They used backbone.js to build their single page appReference: https://developers.soundcloud.com/blog/building-the-next-soundcloud
They used backbone.js to build their single page app Reference: https://developers.soundcloud.com/blog/building-the-next-soundcloud
I didn’t get they said ….