[paul.fr]

If you run a bar of soap through bubbles created by bubble bath, the bubbles start popping. Why is that?

[Ians Daddy]

There may be a chemist here to better answer your question, but I'll take a swing at it.
I know that you can catch a bubble if the catching surface has a coating of the same bubble material. It could be that the chemical breakdown of the two soaps differ. The bar soap would have a different ph level. Maybe more astringent.
When cooking rice or pasta, if it starts to boil over, you touch it with a little butter (an oil, and soap is an oil too) and it goes down. Or the head on a beer goes down if touched by the oil from your finger. This may be the same concept or could be way off, but it's how I imagine it.

Just a thought.

[Edster]

The bar is hydrophilic and the bubbles have water content.

[lyner]

Or the head on a beer goes down if touched by the oil from your finger.

What are you doing washing your hands in beer? You're supposed to DRINK the stuff!!!

[Bored chemist]

I don't know the answer to the question but re "you touch it with a little butter (an oil, and soap is an oil too)". Butter isn't an oil and nor is soap.

[Ians Daddy]

Hey, if I can use it as a lube... it's oil.

[chris]

Ian's Daddy - you're back! Fantastic! It's only been 6 years!

Chris

[Ians Daddy]

Only 6 years?! Hell, I've made girls wait longer than that.
It's good to be back.

Did I miss anything?