This is usually a difficult solution for the structural engineer and also uneconomical, but let me tell you about it.
This is considered one of the most famous cantlivers nowadays.
The cantilevered slab is the slab that is supported by a single support, the bending moment is too high so the thickness becomes large to remain safe under the loads and to resist the deflection which will be the most critical problem in this case.
as in this photo the only support is this far wall with no side supports which makes the slab look unsafe to ordinary people, but as a civil engineer, it is designed for this so it is safe.