Try any single monster encounter where the monster gets hit by Blinding Spittle or Glitterdust.
Or any dragon encounter where dragon gets hit with Shivering Touch.
Or any large group encounter where they get webbed and die.
Any Golem encounter where the golem got buried under mounds of druid summons and beaten to death.
Any encounter ever where the words "time stop" were uttered.
Etc.
Quite easy for a Wizard to trivialize many encounters. Fighters... not so much. They tended to whack things for pretty good damage, but they never really shined, even in combat. Outside of combat, welp.
I guess since I never ran into the problem of one or two classes consistently outshining the rest of the party, I must have done something improper when building encounters to challenge my party.
As for a dragon encounter, I can't imagine any dragon in 3E that could cast spells of at least level 2 that wouldn't have Scintillating Scales prepared and ready to go (if not precast) - it would allow the dragon to add its natural armor bonus to its touch AC (as one player in my group said, "what dragon wouldn't be using it?") and make it nearly invulnerable to touch attacks and ranged touch attacks until it's dispelled. On top of that, Shivering Touch required a touch attack, not a ranged touch... and a wizard is going to have to suck up an AoO charging in to touch a dragon.