So you have a nebula and in the nebula you have a planet.

At a certain point as you travel toward the planet, the planet goes from invisible to "popping" in your face. It wouldnt be so bad it it was small when it "pops" but it is huge and there is clearly a point where it goes from invisible to full visibilty with no transition, hence why i use the phrase "popping".
At the same moment it pops, if you look backwards, you actually cant see the nebula you have travelled through, its as though your in open space.

Would be interested to hear any solutions or ideas on this.