1. The worst of the smell is the sulfer, and most of this is released when the eggs are cracked open after boiling. Somebody might suggest to her that she crack the eggs open, and maybe cut them in half, at home, and after they air out a bit, put them in a container and bring to work.
2. YES, boiled eggs do have a sulfer smell and they do smell bad to most any person, when they are first opened.
3. While it doesn't smell like sulfer, most microwave popcorn does have a very strong odor that can be smelled upon entering the entire vicinity. Not like potato chips or nuts or other snacks.
4. The "crunch... Crunch... CRUNCH... sounds of somebody eating popcorn, especially if they are not trying to be very very discreet, can also be as offensive to some as the smell of foods.
5. Cats do not have an offensive odor like doggie smell. If your cat is an indoor cat, and there is a problem with kitty litter that is not in an area away from the living area and is not changed every day... That could indeed be an issue. I would hate to think that I had a pet that I never touched or never even came close to the clothing I was wearing or anything that it might come in contact with.
6. The cat comment shows that this person has no respect, and will not only disrespect co-workers, but hurl that kind of comment at them. Knowing that this is who you are dealing with, if I were to try to approach this issue, it would be in a very very general way with supervisors... Not directly mentioning this one co-worker and their lunch. Be prepared for your popcorn to also be deemed off limits if fresh-air rules are enforced.