How can I prevent suds from spewing out my toilet?

Recently suds spouted from inside my toilet. The plumber concluded that someone on a higher floor used too much soap, but plumber can't pinpoint which.
How can I foolproof my toilet from all these suds overflowing again, particularly when I am traveling away for business?
Anyone got better ideas than buying quick dams, flood bags, barriers?
Question from user user1147844 at stackexchange.
Answer:
You'd have to plug up the toilet exit somehow. Plumbers use inflatable "test balls" to plug drains, they are available at many of the larger hardware stores and certainly at plumbing supply outlets. It's just a rubber ball with a length of tubing with a Schrader valve on the end. Requires a standard air/bicycle tire pump to inflate. Get the right size, which would be something like 2-3 inches.
Answer from user kreemoweet at stackexchange.

Recently suds spouted from inside my toilet. The plumber concluded that someone on a higher floor used too much soap, but plumber can't pinpoint which.
How can I foolproof my toilet from all these suds overflowing again, particularly when I am traveling away for business?
Anyone got better ideas than buying quick dams, flood bags, barriers?
Question from user user1147844 at stackexchange.
Answer:
You'd have to plug up the toilet exit somehow. Plumbers use inflatable "test balls" to plug drains, they are available at many of the larger hardware stores and certainly at plumbing supply outlets. It's just a rubber ball with a length of tubing with a Schrader valve on the end. Requires a standard air/bicycle tire pump to inflate. Get the right size, which would be something like 2-3 inches.
Answer from user kreemoweet at stackexchange.

