I read some review before purchase this product . what concerned I be when other mention that the water spill over or bubble over onto counter top . but after use this product for a while , I do not know where those reviewer get that idea . it be never bubble over and I think the only reason why it will bubble over be if you put in too much water . and the hard crust will only form if you leave it on warm for a extended period of time . besides , the manual mention that there will be some crust formation so I take that as be forewarn . this be a great product and it do what it say it will do so I will recommend it to everyone . I have not use it for that long so I can not comment on the durability though .