The Shach (al Hatorah) writes that they camped in this place even though there was no water. One may ask why there was no water, as the be'er was traveling with them. He answers by quoting the Gemara (Bava Kama 17A) that states: "There is no water other than Torah." Thus, the pasuk is saying that they were being lax in their Torah study and, as a result, they did not have water to quench their thirst.
This is hinted to from the words: "There was no water there." This indicates that there was no water there, but there was water in other places. When the people did learn Torah properly, the be'er provided water, but when they did not learn enough, the be'er did not provide water.