Most of my kitchen problems are my own darned fault. When I find a product that saves me from myself, it makes me very happy—like when I tried the Kuhn Rikon Spill Stopper ($12-$35).
My self-imposed disasters usually go something like this: I put potatoes into a pot of cold water and crank up the heat, waiting for it to come to a boil so I can lower it to a simmer for the duration of the cooking time. Then I get impatient and slam a cover on the pot. Then I get distracted, leave the room, and the pot boils over. It never fails. If I leave a pot uncovered it may not boil over, but it'll probably at least sputter and spew a bit, making a mess on my stove. At worst, I've had spillovers that extinguished the flame, which is downright dangerous.
The Spill Stopper is a big concave silicone disk that's designed to stop spillovers. There's a removable piece in the center that acts as a vent and allows liquid to bubble up and collect in the "bowl" of the Spill Stopper rather than spilling over the sides of the pot.
I purposely set a pot of potatoes on high boil with the Spill Stopper on top and waited for disaster to strike. I giggled with delight when I saw the liquid bubbling madly in the center without a single drop spilling over the sides.
While the Spill Stopper looks most dramatic when working with things that tend to get foamy, like potatoes or pasta, it also worked to thwart spillovers any time I had a pot that was filled perilously close to the top. Yes, I know I shouldn't do that. But I do.
It also works as a universal lid, as long as you don't mind a little air venting. At about 12 inches in diameter, the one I received fit most of my cookware except the very largest and smallest. (Other sizes are available as well: 10-inch, 13-inch, and 6.5-inch.)
You can also use it as a splatter guard by removing the center piece to vent steam while frying. You'll still get some spattering through that center portion, but even the mesh splatter guards aren't perfect. You can also flip it over to use it as a plate cover, vented or not, in the microwave.
The Spill Stopper is dishwasher safe.
Disclaimer: Testing samples were provided to Serious Eats.