I too identify with the hunger-nausea-sneeze pattern described above. It is so frustrating to have swallowed the first bite of a meal only to have a nearly instant rise of extreme nausea followed by an unstoppable violent sneeze which sprays the ready-to-swallow second bite out of the mouth like an explosive spit take.
BTW I am not a smoker but have been in the past but not for years now.
I have one possible explanation. My mother has nearly the same behaviors along with at least 3 of her siblings. Her doctor made an association between this unnamed condition and a known acid reflux condition she has. His speculation was that maybe the duodenum (I think that's the part) not opening and closing as it should could be at the cause of both issues.
I too have mild reflux but not bad enough to medicate. I inherited several quirks from my mom's side of the family and I suspect this is just another.