Here is an explanation that best describes 'death wobble' in as laymen's terms as I can provide;
Too much scrub radius is the biggest culprit.
Death wobble [on cars with good componentry] is caused by forces fighting each other. All it takes is a bump to start this chain reaction.
Generally, 'toe' is used to negate the effects of 'camber thrust'. Negative camber needs toe-out, positive requires toe-in.
Designers of vehicle geometry try to put the kingpin inclination close to, or slightly inside, the centerline of the tire.
Because of kingpin inclination, if there was zero caster the wheels would 'flop over' when turned either direction.
To correct this ,the manufacturers add positive caster so the outside wheel is closer to vertical during cornering [a side effect is the vehicle will 'straighten up' when the steering wheel is released].
Sharper turning circles require more caster, but manufacturers avoid this and try to keep caster to a minimum for normal turning at average speeds ['scrubbing' tires in a parking lot isn't a safety issue]
Technically, if there were NO tie-rod, increased caster would toe the front wheels inwards [due to vertical forces]. To reduce these loads, common practice is to add some scrub radius, which would toe the front wheels outwards, causing the two geometrical forces to counteract each other.
Excessive scrub radius isn't an issue in a straight line with no bumps because the drag [toe-out forces] counteract each other [it does however 'load up' componentry more].
When only one wheel hits a bump with excessive scrub radius, that particular side will suddenly toe-out snapping the steering. As no road has zero bumps, this is the norm.
Common practice is to increase positive caster with the myth that this alone increases straight line stability.
Excessive scrub radius combined with excessive positive caster in a lightweight vehicle is where the oscillations will start [all it takes is a bump for the scrub radius to start the chain reaction]
The lighter [or more raised] the vehicle, the worse it is because caster will lift the vehicle instead of forcing itself to return to a straight line position.
If the L/H wheel hits a bump, the steering will snap to the left, causing the caster on the left to try to steer to the right. These oscillations will go past the straight ahead centerline because there is excessive caster for the weight/height of the vehicle.
Oscillations of this type are always magnified along a solid axle steering suspension.
The closest thing to a 'fix' would be to reduce caster and reduce scrub radius, all other methods are patches [providing componentry is in good condition].
Hope this helps you understand this effect..
(btw-many here seem to confuse 'caster' & 'angle of attack'. Imo-the advantage of C/A drop brackets is the maintainence of C/A attack angle, not increased caster-which can conspire to magnify 'death wobble' with scrub radius changes)