A common way to achieve that look is a mounted float display rather than a traditional frame. One typical method is:

• print on high-quality satin or metallic paper
• mount the print to a thin aluminum sheet for rigidity and a clean modern look
• laminate the front for a smooth matte or soft finish
• attach spacer blocks to the back so it stands off the wall and appears to float

That produces the borderless, “popping off the wall” presentation you described. The clear front you noticed may have been part of the lamination or display finish, but the key idea is usually a print mounted to aluminum with rear blocks/spacers instead of a visible frame.

If you want to recreate it, search for labs or framers offering mounted aluminum prints, laminated photographic prints, or float-mounted wall displays.