Onlookers at park witness as a bison is boiled in the scalding Grand Prismatic Spring
                                
                                
                                    (Newser) -
                                    Visitors at Yellowstone National Park last month got what  CBS News  calls a "front row to nature," though a horrifying one. Dozens of tourists were huddled around Grand Prismatic Spring, near the Old Faithful geyser, on the morning of June 21 when a bison slipped into a shallow...