The above describes a state in which an action or event might take place any minute. Replace ます at the end of Vます with そう. V(ます)そう functions as a na-adjective in the same way as A(い)/A(な)-そう does.
上着のボタンが取れそうです。
The button looks as if it will come off.
切れそうなひもはすててください。
Please throw away a string which looks like it is about to snap.
木がたおれそうになりました。
A tree has leaned, looking as if it will fall down.