When light goes from a more dense medium to a less dense medium, it bends away from the normal, as in the image
When light goes from a less dense medium to a more dense medium it bends towards the normal, as in the pic
But is it possible that light turns all the way around the normal? I think it should be possible as it doesn't violate fermat's principle, or does it? (see the image that follows)
NOTE(1): I have specified the interface in pic 3 so as to show that this is not a case of total internal reflection
NOTE(2): please explain in regards to fermat's principle, as you would to a person just been introduced to ray optics