In my experience, getting watering right is the number one thing houseplant owners struggle with. One common occurrence is when incorrect watering turns soil hydrophobic, meaning it won't absorb any water or it dries unevenly.
This is the result of common indoor plant mistakes where soil is left to stay dry for too long, the potting mix is old, or it can be the result of intense heat. These things actually turn soil repellent to water, so you'll see it pool on the surface and struggle to absorb.
