The wooden spoon across a boiling pot is one of those kitchen tricks many people hear from parents or grandparents. It sounds too simple to be true, but there is actually some logic behind it.
When water, pasta, potatoes, or soup starts boiling, bubbles rise and build up foam on the surface. If that foam keeps growing, it can spill over the edge of the pot. A dry wooden spoon can sometimes break the bubbles as they rise. Wood also does not heat up as quickly as metal, so when the bubbles touch the cooler spoon, they may collapse before overflowing.
That is why the trick can work for a short time, especially if the pot is only starting to foam. However, it is not a perfect solution. If the heat is too high, the pot is too full, or the food creates a lot of starch, the bubbles can still rise past the spoon and spill over anyway.
The safest and most reliable way to prevent boiling over is to lower the heat once the water reaches a strong boil. Using a larger pot also helps, especially for pasta or potatoes.
So your aunt is not completely wrong. The wooden spoon trick can help, but it should not be trusted on its own. It is more of a helpful old kitchen habit than a guaranteed fix.
