I don't believe that is possible with glass shelves.

Good luck!

There are supports that are virtually invisible, but some form of support is going to be visible unless your wall is relatively narrow and the glass is fit into slots.

This is a little tricky but I've actually done it. You need laminated or tempered glass so you have enough tensile strength to support the shelf. Take a U channel that is the same dimension as your glass and router a notch into the vertical 2x4s. Set the U channel into the notch and secure it, we used counter sunk screws in an extruded aluminum channel. Paint the channel flat black so you don't see any reflection from the metal. Set the glass with bead of silicone in at the back with enough on it so the silicon squeezes out. Drywall around and you are done. The big question is always how big a channel in relation to the projection. I would say 1/3rd of the projection is definitely adequate, we used a 2" deep channel for an 8" piece of glass so the projection was 6" with 2" in the channel.